Buggy code:
public HashMap previousSessionContainers = new HashMap ( 5 ) ; private ThreadLocal containerInitializationInProgress = new ThreadLocal ( ) ; public boolean batchContainerInitializations = false ; public HashMap containerInitializersCache = new HashMap ( 5 ) ; private ThreadLocal classpathsBeingResolved = new ThreadLocal ( ) ; public JavaWorkspaceScope workspaceScope ; private WeakHashSet stringSymbols = new WeakHashSet ( 5 ) ; private WeakHashSetOfCharArray charArraySymbols = new WeakHashSetOfCharArray ( 5 ) ; public static final String CP_VARIABLE_PREFERENCES_PREFIX = ( JavaCore . PLUGIN_ID ) + ".classpathVariable." ; public static final String CP_CONTAINER_PREFERENCES_PREFIX = ( JavaCore . PLUGIN_ID ) + ".classpathContainer." ; public static final String CP_ENTRY_IGNORE = "##<cp<seq2seq4repair_space>entry<seq2seq4repair_space>ignore>##" ; public static final IPath CP_ENTRY_IGNORE_PATH = new Path ( JavaModelManager . CP_ENTRY_IGNORE ) ; private static final int VARIABLES_AND_CONTAINERS_FILE_VERSION = 1 ; public static final String CPVARIABLE_INITIALIZER_EXTPOINT_ID = "classpathVariableInitializer" ; public static final String CPCONTAINER_INITIALIZER_EXTPOINT_ID = "classpathContainerInitializer" ; public static final String FORMATTER_EXTPOINT_ID = "codeFormatter" ; public static final String COMPILATION_PARTICIPANT_EXTPOINT_ID = "compilationParticipant" ; public static final String JAVA_SOURCE_CONTENT_TYPE = ( JavaCore . PLUGIN_ID ) + ".javaSource" ; public static final IPath VARIABLE_INITIALIZATION_IN_PROGRESS = new Path ( "Variable<seq2seq4repair_space>Initialization<seq2seq4repair_space>In<seq2seq4repair_space>Progress" ) ; public static final IClasspathContainer CONTAINER_INITIALIZATION_IN_PROGRESS = new IClasspathContainer ( ) { public IClasspathEntry [ ] getClasspathEntries ( ) { } public String getDescription ( ) { } public int getKind ( ) { } public IPath getPath ( ) { } public String toString ( ) { } } ; private static final String BUFFER_MANAGER_DEBUG = ( JavaCore . PLUGIN_ID ) + "//debug//buffermanager" ; private static final String INDEX_MANAGER_DEBUG = ( JavaCore . PLUGIN_ID ) + "//debug//indexmanager" ; private static final String COMPILER_DEBUG = ( JavaCore . PLUGIN_ID ) + "//debug//compiler" ; private static final String JAVAMODEL_DEBUG = ( JavaCore . PLUGIN_ID ) + "//debug//javamodel" ; private static final String CP_RESOLVE_DEBUG = ( JavaCore . PLUGIN_ID ) + "//debug//cpresolution" ; private static final String ZIP_ACCESS_DEBUG = ( JavaCore . PLUGIN_ID ) + "//debug//zipaccess" ; private static final String DELTA_DEBUG = ( JavaCore . PLUGIN_ID ) + "//debug//javadelta" ; private static final String DELTA_DEBUG_VERBOSE = ( JavaCore . PLUGIN_ID ) + "//debug//javadelta//verbose" ; private static final String HIERARCHY_DEBUG = ( JavaCore . PLUGIN_ID ) + "//debug//hierarchy" ; private static final String POST_ACTION_DEBUG = ( JavaCore . PLUGIN_ID ) + "//debug//postaction" ; private static final String BUILDER_DEBUG = ( JavaCore . PLUGIN_ID ) + "//debug//builder" ; private static final String COMPLETION_DEBUG = ( JavaCore . PLUGIN_ID ) + "//debug//completion" ; private static final String RESOLUTION_DEBUG = ( JavaCore . PLUGIN_ID ) + "//debug//resolution" ; private static final String SELECTION_DEBUG = ( JavaCore . PLUGIN_ID ) + "//debug//selection" ; private static final String SEARCH_DEBUG = ( JavaCore . PLUGIN_ID ) + "//debug//search" ; private static final String SOURCE_MAPPER_DEBUG_VERBOSE = ( JavaCore . PLUGIN_ID ) + "//debug//sourcemapper" ; public static final String COMPLETION_PERF = ( JavaCore . PLUGIN_ID ) + "//perf//completion" ; public static final String SELECTION_PERF = ( JavaCore . PLUGIN_ID ) + "//perf//selection" ; public static final String DELTA_LISTENER_PERF = ( JavaCore . PLUGIN_ID ) + "//perf//javadeltalistener" ; public static final String VARIABLE_INITIALIZER_PERF = ( JavaCore . PLUGIN_ID ) + "//perf//variableinitializer" ; public static final String CONTAINER_INITIALIZER_PERF = ( JavaCore . PLUGIN_ID ) + "//perf//containerinitializer" ; public static final String RECONCILE_PERF = ( JavaCore . PLUGIN_ID ) + "//perf//reconcile" ; private static final String ENABLE_NEW_FORMATTER = ( JavaCore . PLUGIN_ID ) + "//formatter//enable_new" ; public static boolean PERF_VARIABLE_INITIALIZER = false ; public static boolean PERF_CONTAINER_INITIALIZER = false ; public static final ICompilationUnit [ ] NO_WORKING_COPY = new ICompilationUnit [ 0 ] ; HashSet optionNames = new HashSet ( 20 ) ; Hashtable optionsCache ; public final IEclipsePreferences [ ] preferencesLookup = new IEclipsePreferences [ 2 ] ; static final int PREF_INSTANCE = 0 ; static final int PREF_DEFAULT = 1 ; static final CompilationParticipant [ ] NO_PARTICIPANTS = new CompilationParticipant [ 0 ] ; public class CompilationParticipants { private CompilationParticipant [ ] registeredParticipants = null ; public CompilationParticipant [ ] getCompilationParticipants ( IJavaProject project ) { } private CompilationParticipant [ ] getRegisteredParticipants ( ) { if ( ( this . registeredParticipants ) != null ) { return this . registeredParticipants ; } ArrayList participants = new ArrayList ( ) ; IExtensionPoint extension = Platform . getExtensionRegistry ( ) . getExtensionPoint ( JavaCore . PLUGIN_ID , JavaModelManager . COMPILATION_PARTICIPANT_EXTPOINT_ID ) ; if ( extension == null ) <START_BUG> return null ; <END_BUG> IExtension [ ] extensions = extension . getExtensions ( ) ; for ( int i = 0 ; i < ( extensions . length ) ; i ++ ) { for ( int j = 0 ; j < ( extensions . length ) ; j ++ ) { IConfigurationElement [ ] configElements = extensions [ j ] . getConfigurationElements ( ) ; for ( int k = 0 ; k < ( configElements . length ) ; k ++ ) { String elementName = configElements [ k ] . getName ( ) ; if ( ! ( "compilationParticipant" . equals ( elementName ) ) ) { continue ; } try { Object execExt = configElements [ j ] . createExecutableExtension ( "class" ) ; if ( execExt instanceof CompilationParticipant ) { participants . add ( execExt ) ; } } catch ( CoreException e ) { Util . log ( e , "Unexpected<seq2seq4repair_space>exception<seq2seq4repair_space>trying<seq2seq4repair_space>to<seq2seq4repair_space>instanciate<seq2seq4repair_space>compilation<seq2seq4repair_space>participant" ) ; } } } } int size = participants . size ( ) ; if ( size == 0 ) return this . registeredParticipants = JavaModelManager . NO_PARTICIPANTS ; this . registeredParticipants = new CompilationParticipant [ size ] ; participants . toArray ( this . registeredParticipants ) ; return this . registeredParticipants ; } } public final JavaModelManager . CompilationParticipants compilationParticipants = new JavaModelManager . CompilationParticipants ( ) ; public static boolean conflictsWithOutputLocation ( IPath folderPath , JavaProject project ) { } public synchronized IClasspathContainer containerGet ( IJavaProject project , IPath containerPath ) { } private synchronized Map containerClone ( IJavaProject project ) { } private HashSet containerInitializationInProgress ( IJavaProject project ) { }

Fix:
return this . registeredParticipants = JavaModelManager . NO_PARTICIPANTS ;